In 1264 Zaccaria was named Genoese ambassador to the Byzantine emperor, Michael VIII Paleologus, who bestowed on him and his brother Manuele the fief of Phocaea, north of Smyrna, with its alum mines. On this foundation the brothers built a commercial empire, trading in North Africa, Spain, France, Flanders, Constantinople, and the Black Sea. Zaccaria returned to Genoa in 1284 and took command of a fleet that blockaded Pisa’s Tyrrhenian port, the Porto Pisano, a naval maneuver that led to Pisa’s committing its fleet to combat. In the resulting Battle of Meloria, Zaccaria’s tactics produced a Genoese victory from which Pisa never recovered.

Leaving Genoa in 1290, Zaccaria served as grand admiral of the fleet of Sancho IV of Castile. Four years later he commanded the fleet of Philip IV of France against England, blockading Flanders in 1299. In about 1301 Zaccaria sailed for Phocaea to protect it against the inroads of Turkish and Catalan pirates and seized the nearby island of Chios. He returned a few years later to Genoa, where he died.